Such three-phase two-level power electronics assemblies commonly have a design comprising a thermally conductive base plate with two faces. On a first face of the base plate, a heat dissipation unit is mounted, and a set of power electronic devices is mounted on a second face of the base plate. The power electronic devices are typically arranged within the three-phase two-level power electronics assembly in rows according to their functions to form logical entities located closely on the base plate.
According to a typical usage of the three-phase two-level power electronics assemblies, connectors for a three phase AC output as well as two chopper DC outputs are provided, as well as connectors for two poles of a DC link. Such a design of the three-phase two-level power electronics assembly is e.g. used in power converters, in particular in static power converters. The power converters, in particular static power converters, are often built as compact and integrated systems to reach high possible performances with increased voltages and switching frequencies. A typical usage of such power converters is in the area of transportation, e.g. in electrically driven locomotives and trains as well as electric railcars or power coaches. In this area, the power converter is often referred to as traction converter.
For the use e.g. in the power converters, the power electronic devices are typically arranged in half-bridges according to their functions, whereby each half-bridge implements a switching function. As discussed here, the power electronic devices are connected to provide a three phase AC output as well as chopper DC outputs at the respective connectors. Because of needs e.g. for electrical connections, the half-bridges are typically arranged in parallel rows on the second face of the base plate.
The power electronic devices refer to electronic components comprising at least one power semiconductor. The power semiconductors typically comprise power diodes and/or power transistors, in particular Insulated-gate bipolar transistors (IGBT). In simple implementations, the power electronic devices comprise IGBTs and power diode, which are chosen and arranged according to the functions of the half-bridges, and which are directly mounted on the base plate. However, depending on in particular voltage and/or current carrying capabilities, it can be required to combine multiple of these power semiconductors in parallel and/or in series. Accordingly, the power semiconductors can be provided in power semiconductor modules, which can be mounted as power electronic devices.
The power semiconductor modules can be formed depending on their functions by different groups of power semiconductors. For Example IGBT modules and diode modules are known in the Art, whereby the IGBT modules comprise IGBTs and power diodes, and the diode modules comprise power diodes. Furthermore, the IGBT modules can implement different functionality depending on the type, number, arrangement, or others of the IGBTs. In a typical design of power semiconductor modules, the power semiconductor modules can be provided as single, double or six packs modules depending on the number of implemented switches. Still further, it is also possible to combine different power semiconductor modules and provide these combined power semiconductor modules as power electronic devices.
In order to operate the power electronic devices, in particular the power transistors, the three-phase two-level power electronics assembly comprises at least one control connector, typically provided as gate connector.
The two poles of the DC link are connected with a common DC bus for the positive and negative pole. The DC link serves as power source for the three-phase two-level power electronics assembly. Hence, the two poles of the DC link are connected to the power electronic devices.
In the area of power electronics, heating is usually an important issue. Heat is generated by the power semiconductors and also by resistive components, or the power semiconductor modules comprising these components. In particular in air-cooled three-phase two-level power electronics assemblies, heating of the components can limit its function and lifetime. Hence, when excessive heating occurs, the power semiconductor devices can be altered and destroyed before end of their designated lifetime. This also increases maintenance of the devices, where the power semiconductor devices are employed. Typically, e.g. in a power converter, multiple power semiconductor devices are used. The failure of already one of the power semiconductor devices can make the entire device unusable. Accordingly, a device with numerous power semiconductor devices has typically a low reliability and requires frequent maintenance.
To dissipate heat, the power semiconductors are typically mounted directly on the base plate. Accordingly, heat generated in the electrical components can be directly dissipated from the second face of the base plate through the base plate to its first face and the heat dissipation unit mounted thereon.
It is also known in the Art to provide cooling mechanisms in order to obtain an adequate availability of the power semiconductor devices and an increased life cycle. A powerful cooling mechanism is water cooling, which requires an installation of a full water circulation circuit, and which is therefore not suitable for all installations. Also in other cases it can be preferred not to use water-cooling. However, when using water cooling, heating can usually be controlled in an efficient and powerful way, which allows high integration of three-phase two-level power electronics assemblies.
In the case of air-cooled three-phase two-level power electronics assemblies, the heat dissipation unit usually comprises cooling rips. To enhance cooling efficiency, fresh air can be provisioned to the three-phase two-level power electronics assemblies. However, a desired integration cannot always be achieved because of insufficient dissipation of generated heat.